题目

Our elder son has been ______ the Continent for several months.   A. knocking about                       B. knocking down                 C. knocking over                        D. knocking off 答案：A在0，，–，–8，＋10，＋19，＋3，–3.4中，整数的个数是（ ）A. 6 B. 5 C. 4 D. 3